Various types of semiconductor devices are known. One of a semiconductor device is a device called an IPM (Intelligent Power Module). This semiconductor device includes a plurality of semiconductor chips, a plurality of die pad portions, a heat radiation plate, a joining layer and an encapsulating resin. The semiconductor chips are respectively arranged in the die pad portions. The die pad portions are joined to the heat radiation plate through the joining layer. The encapsulating resin covers the semiconductor chips, the die pad portions, the heat radiation plate and the joining layer. An IPM semiconductor device is known in the art.
Some semiconductor devices are mounted on a substrate (circuit substrate). When an IPM semiconductor device is mounted on a substrate, the heat radiation plate directly faces a relatively large radiator existing outside the semiconductor device. In order to assure good heat transfer between the heat radiation plate and the radiator, heat radiating grease is often interposed between the heat radiation plate and the radiator. Therefore, each time the semiconductor device is mounted on the substrate, it is necessary to apply the heat radiating grease on the heat radiation plate or the radiator. This poses an impediment in efficiently mounting the semiconductor device.
It is costly to come by an adhesive agent that will become the joining layer in the semiconductor device. In a manufacturing process of the semiconductor device, the die pad portions and the heat radiation plate are joined together prior to forming a resin encapsulation portion. Forming the resin encapsulation portion and joining the die pad portions and the heat radiation plate together are performed independently of each other. This hampers manufacturing efficiency of the semiconductor device.
Different sorts of semiconductor devices are known in the art. As one example of the different semiconductor devices, a semiconductor device including a semiconductor chip, a die pad portion, an encapsulating resin and a heat sink is available. The semiconductor chip is arranged in the die pad portion. The heat sink is adhesively joined to the opposite surface of the die pad portion from the surface on which the semiconductor chip is arranged. The encapsulating resin covers the semiconductor chip, the die pad portion and the heat sink. The heat sink and the adhesive agent used in manufacturing the semiconductor device are relatively expensive. This makes it difficult to sufficiently reduce the manufacturing cost of the semiconductor device.
In a related art, an integrated circuit device (a semiconductor device) is configured to cover a lead frame with a resin having a high heat radiation property. In this related art, a heat sink is not joined to a die pad portion by an adhesive agent. This makes it possible to reduce the cost involved in providing a heat sink and an adhesive agent.
More specifically, the integrated circuit device disclosed in the related art includes a lead frame, a power element and a resin. The power element is mounted on the lead frame. The resin includes a low stress resin and a high heat radiation resin. The low stress resin covers the power element and the lead frame. The high heat radiation resin covers the opposite surface of the lead frame from the surface on which the power element is arranged. In the integrated circuit device disclosed in the related art, an attempt is made to prevent exfoliation of the high heat radiation resin from the low stress resin. However, if the high-heat radiating resin and the lead frame are not strongly joined together, the high-heat radiating resin may be separated from the lead frame even though the high-heat radiating resin and the low stress resin are firmly bonded together.